# US 9,753,207 B2 · Light guide plate, surface light source device, transmissive display device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,753,207 B2 - Document ID: US9753207B2 - Status: Granted - Kind: B2 - Application number: 15/303,853 - Filed: 2016-02-10 - Published: 2017-05-11 - Granted: 2017-09-05 - Earliest claimed: 2015-02-20 - Assignees: Dai Nippon Printing Co., Ltd. - Applicants: Dai Nippon Printing Co., Ltd. - Inventors: Eiji Asano; Daijirou Kodama; Kazuki Matsumoto; Keiko Kitano - Web page: https://patentgrep.com/patent/US9753207B2 ## CPC - G02B 6/0036: {2-D arrangement of prisms, protrusions, indentations or roughened surfaces} - G02B 6/0038: {Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide} - G02B 6/0053: {Prismatic sheet or layer; Brightness enhancement element, sheet or layer} - G02B 6/0058: {varying in density, size, shape or depth along the light guide} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A light guide plate having light-emitting-side unit optical shapes arranged on a light emitting surface in a direction perpendicular to a light guide direction and a thickness direction of the light guide plate. The optical shape extends in the light guide direction and has a groove shape recessed in the light emitting surface, and a bottom of the groove is formed on a surface which is concave toward the back surface side. Inclined surfaces which are inclined from an edge portion toward the bottom side are formed in two end portions of the concave surface in an arrangement direction. When a width of the optical shape in the arrangement direction is W21, a maximum inclination angle θ of the inclined surface relative to the light emitting surface satisfies 20°≦θ≦45°, and a radius of curvature r of the concave surface satisfies r≧W21/(4×sin θ). ## Claims ### Claim 1 A light guide plate having a light incident surface on which light is incident, a light emitting surface which intersects the light incident surface and emits light, and a back surface which faces the light emitting surface, the light guide plate emitting the light from the light emitting surface while guiding the incident light from the light incident surface in a light guide direction, wherein a plurality of light-emitting-side unit optical shapes are arranged in the light emitting surface in a direction which is perpendicular to the light guide direction and is perpendicular to a thickness direction of the light guide plate, wherein the light-emitting-side unit optical shape extends in the light guide direction and is formed in a groove shape which is recessed from the light emitting surface, and a bottom of the groove shape is formed on a concave surface which is concave toward the back surface side, wherein flat inclined surfaces which are inclined from an edge portion where recessing from the light emitting surface is started toward the bottom side are formed in two end portions of the concave surface in an arrangement direction, and wherein, when a width of the light-emitting-side unit optical shape in the arrangement direction is denoted by W21, a maximum inclination angle θ of the inclined surface with respect to the light emitting surface satisfies 20°≦θ≦45°, and a radius of curvature r of the concave surface satisfies r≧W21/(4×sin θ). ### Claim 2 (depends on 1) The light guide plate according to claim 1, wherein a ratio R=W22/W21 of a width W22 of the concave surface to the width W21 of the light-emitting-side unit optical shape in the arrangement direction of the light-emitting-side unit optical shape is 50%≦R≦80%. ### Claim 3 (depends on 1) The light guide plate according to claim 1, wherein a flat portion which is substantially parallel to the light emitting surface is provided between the adjacent light-emitting-side unit optical shapes. ### Claim 4 (depends on 3) The light guide plate according to claim 3, wherein a width W23 of the flat portion in the arrangement direction of the light-emitting-side unit optical shape is 0.5 μm≦W23≦2.5 μm. ### Claim 5 (depends on 4) The light guide plate according to claim 4, wherein the width W23 of the flat portion in the arrangement direction of the light-emitting-side unit optical shape is 0.5 μm≦W23≦2.0 μm. ### Claim 6 (depends on 3) The light guide plate according to claim 3, wherein at least a portion of the flat portions are different from other flat portions in a thickness direction in terms of height. ### Claim 7 (depends on 1) The light guide plate according to claim 1, wherein a plurality of back-surface-side unit optical shapes are arranged on the back surface in the light guide direction, wherein the back-surface-side unit optical shape is convex toward a back surface side and includes a first inclined surface portion which is located in the light incident surface side, a second inclined surface portion which is located in the other side facing the first inclined surface portion to totally reflect at least a portion of the incident light, and a top surface portion which is located between the first inclined surface portion and the second inclined surface portion, and wherein the top surface portion includes a contact portion which is in contact with a reflection member which is arranged on the back surface side of the light guide plate. ### Claim 8 (depends on 1) A surface light source device comprising: the light guide plate according to claim 1; a light source unit which is provided at a position facing the light incident surface of the light guide plate and emits light to the light incident surface; and a deflection optical sheet which is arranged on a light emitting surface side of the light guide plate and has a deflection function of deflecting light emitted from the light guide plate to a normal direction of a sheet surface thereof or a direction where an angle with respect to the normal direction is to be decreased. ### Claim 9 (depends on 8) A transmissive display device comprising: the surface light source device according to claim 8; and a transmissive display unit which is illuminated from a back surface side by the surface light source device.